Feature: Cache dictionaries

Cache dictionaries

There is some cost to dictionaries, so it might be worth caching them (especially with .dic+.aff).

Implementation

Dictionaries will go to a specific directory and actions/cache will track the directory.

The dictionary retrieval code can choose to skip retrieving any file(s) it already has.

Invalidation

Each dictionary's ETAG and url should be stored.

If the url is different, invalidate. Use the ETAG to retrieve (or not) the content.

Clearing cache entries manually

1. You can get a list of caches using actions/cache: list-github-actions-caches-for-a-repository
2. You can delete a cache entry by id using actions/cache: delete-a-github-actions-cache-for-a-repository-using-a-cache-id